Selective activation of adrenergic β1 receptors induces heme oxygenase 1 production in RAW264.7 cells

AbstractWe hypothesized that catecholamines through β-adrenoceptor might modulate macrophage function. We showed that isoproterenol concentration-dependently induced HO-1 production through β1-but not β2-adrenoceptor. Production was increased by forskolin and inhibited by pretreatment with the PKA inhibitor, H-89. Furthermore, induction of HO-1 by isoproterenol effectively protected RAW264.7 cells from effects of glucose oxidase treatment, which was abrogated either by HO-1 inhibitor, ZnPP IX and β-adenoceptor antagonist, propranolol. Thus, stimulation of HO-1 production through β1-adenoceptors, and via the PKA pathways by isoproterenol, can enable RAW264.7 cells to resist oxidant stress, suggesting that catecholamine hormones may be necessary, at least, to maximize defending role of macrophages

A Novel Design of an Inner Rotor for Optimizing the Air-Gap Magnetic Field of Hollow-Cup Motors

In order to obtain a high power density, spacecraft usually use hollow-cup motors with trapezoidal air-gap magnetic field waveforms. However, due to structural issues, the hollow-cup motor has the problem that the waveform of the air-gap magnetic field is inconsistent with the ideal trapezoidal waveform, which causes torque ripples. In order to reduce torque ripples, the existing method only changes the structure of PMs; the changed PMs are difficult to magnetize and manufacture, which causes the air-gap magnetic field waveform to be unsuitable as the ideal waveform. This paper proposes a novel design of an inner rotor of a hollow-cup motor with an eccentric inner rotor based on the characteristics that the hollow-cup motor has inner and outer rotors and the two rotors rotate synchronously during operation. First, the influencing factors of the air-gap magnetic field are analyzed and the mathematical model of the eccentric inner rotor is established. Then, an eccentric model is established by finite element analysis, which proves that the eccentricity of the inner rotor can make the air-gap magnetic field waveform closer to the ideal trapezoid. Finally, a prototype based on the optimal eccentricity value is developed, verifying the effectiveness of the novel design of the inner rotor

Analysis of Air-Gap Magnetic Field and Structure Optimization Design of Hollow-Cup Motor

Hollow-cup motors are usually used in spacecraft because of their low power consumption and high control accuracy. However, because the air-gap between the permanent magnets (PMs) and the rotor of the hollow-cup motor is uniform, the sinusoidal characteristic of the air-gap magnetic field waveform is inferior and the total harmonic distortion (THD) is large, resulting in torque ripple. For the large air-gap hollow-cup motor, the existing methods for optimizing the sinusoidal characteristics of the air gap magnetic field change the shape of PMs, but the changed PMs are difficult to manufacture and magnetize, resulting in the methods being limited and not being able to achieve the ideal optimization effect for the hollow-cup motor. Based on the characteristics of the inner rotor and outer rotor rotating synchronously during operation, a new structure design of the hollow-cup motor with an eccentric inner rotor is proposed instead of changing the PMs’ shape. Firstly, the mathematical model of the hollow-cup motor is established. Then, the FEM shows that the inner rotor’s eccentricity can bring the air-gap magnetic field waveform closer to the ideal sinusoidal waveform and can effectively reduce the THD. Finally, a prototype with the optimal eccentricity value is made for experimental verification

Analysis and design of permanent magnet biased magnetic bearing based on hybrid factor

In this article, hybrid factor is proposed for hybrid magnetic bearing. The hybrid factor is defined as the ratio of the force produced by the permanent magnet and the forces produced by the permanent magnet and current in hybrid magnetic bearing. It is deduced from a certain radial hybrid magnetic bearing using its important parameters such as the current stiffness and displacement stiffness at first and then the dynamic model of magnetically suspended rotor system is established. The relationship between structural parameters and control system parameters is analyzed based on the hybrid factor. Some influencing factors of hybrid factor in hybrid magnetic bearing, such as the size of the permanent magnet, length of air gap, and area of the stator poles, are analyzed in this article. It can be concluded that larger hybrid factor can be caused by the smaller power loss according to the definition of hybrid factor mentioned above. Meanwhile, the hybrid factor has a maximum value, which is related to control system parameters such as proportional factor expect for structural parameters. Finally, the design steps of parameters of hybrid magnetic bearing can be concluded

Analysis of Air-Gap Magnetic Field and Structure Optimization Design of Hollow-Cup Motor

Hollow-cup motors are usually used in spacecraft because of their low power consumption and high control accuracy. However, because the air-gap between the permanent magnets (PMs) and the rotor of the hollow-cup motor is uniform, the sinusoidal characteristic of the air-gap magnetic field waveform is inferior and the total harmonic distortion (THD) is large, resulting in torque ripple. For the large air-gap hollow-cup motor, the existing methods for optimizing the sinusoidal characteristics of the air gap magnetic field change the shape of PMs, but the changed PMs are difficult to manufacture and magnetize, resulting in the methods being limited and not being able to achieve the ideal optimization effect for the hollow-cup motor. Based on the characteristics of the inner rotor and outer rotor rotating synchronously during operation, a new structure design of the hollow-cup motor with an eccentric inner rotor is proposed instead of changing the PMs’ shape. Firstly, the mathematical model of the hollow-cup motor is established. Then, the FEM shows that the inner rotor’s eccentricity can bring the air-gap magnetic field waveform closer to the ideal sinusoidal waveform and can effectively reduce the THD. Finally, a prototype with the optimal eccentricity value is made for experimental verification

Measurement and Analysis of Magnetic Properties of Permalloy for Magnetic Shielding Devices under Different Temperature Environments

The relative permeability, coercivity, and remanence of permalloy are closely related to the performance of magnetic shielding devices. In this paper, the relationship between the magnetic properties of permalloy and the working temperature of magnetic shielding devices is measured. Firstly, the measurement method of permalloy properties based on the simulated impact method is analyzed. What is more, a magnetic property test system consisting of a soft magnetic material tester and a high–low temperature chamber for permalloy ring samples at different temperatures was established to measure DC and AC (0.01 Hz to 1 kHz) magnetic properties at different temperatures (−60 °C to 140 °C). Finally, the results show that compared with room temperature (25 °C), the initial permeability (μi) decreases by 69.64% at −60 °C and increases by 38.23% at 140 °C, and the coercivity (hc) decreases by 34.81% at −60 °C and increases by 8.93% at 140 °C, which are the key parameters in the magnetic shielding device. It can be concluded that the relative permeability and remanence of permalloy are positively correlated with temperature, while the saturation magnetic flux density and coercivity are negatively correlated with temperature. This paper is of great significance to the magnetic analysis and design of magnetic shielding devices